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53 lines
1.2 KiB
53 lines
1.2 KiB
scan = ARGF.read.lines(chomp: true)
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cave = scan.each.with_object({}) {|line, cave|
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line.split(" -> ")
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.map { _1.split(?,).map(&:to_i) }
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.each_cons(2) {|(ax,ay),(bx,by)|
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Range.new(*[ax, bx].sort).each do |x|
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Range.new(*[ay, by].sort).each do |y|
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cave[[x, y]] = ?#
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end
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end
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}
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}
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def cave.to_s
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x_min, x_max = keys.map(&:first).minmax
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y_min, y_max = keys.map(&:last).minmax
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(0..y_max+1).map {|y|
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(x_min-1..x_max+1).map {|x|
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self.fetch([x, y], ?.)
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}.join
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}.join("\n")
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end
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def pour_sand(cave, stop:)
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return enum_for(__method__, cave, stop:) unless block_given?
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loop do
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# puts cave
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pos = [500, 0]
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while next_pos = [0, -1, 1].map {|dx| pos.zip([dx, 1]).map { _1 + _2 }}.find { cave[_1].nil? }
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pos = next_pos
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break if stop.(*pos)
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end
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break if stop.(*pos)
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cave[pos] = ?o
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yield pos
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end
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end
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y_max = cave.keys.map(&:last).max
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# part one
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p pour_sand(cave, stop: ->(_, y) { y >= y_max }).count
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# part two
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cave.delete_if { _2 == ?o } # reset cave
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cave.default_proc = ->(_,(_,y)) { y == y_max + 2 ? ?# : nil }
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p pour_sand(cave, stop: ->(x, y) { [x, y] == [500, 0] }).count + 1
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